Sleep is important for good health. Frequent disturbances during sleep or sleep fragmentation can have severe consequences including day-time sleepiness (with the attendant possibility of motor-vehicle accidents), poor mentation, memory problems, depression and hypertension. For example, a person with nasal congestion may snore to a point that it disturbs that person's ability to sleep. Similarly, people with SDB are also likely to disturb their partner's sleep. One known effective form of treatment for patients with SDB is nasal continuous positive airway pressure (nasal CPAP) applied by a flow generator (e.g., a servo-controlled blower via a connecting hose and patient interface. In some forms the supply of air at positive pressure is delivered to both the nose and mouth, such as with a mask. The positive pressure can prevent a collapse of the patient's airway during inspiration, thus preventing events such as snoring, apnoeas or hypopnoeas and their sequelae.
Such positive airway pressure may be delivered in many forms. For example, a positive pressure level may be maintained across the inspiratory and expiratory levels of the patient's breathing cycle at an approximately constant level. Alternatively, pressure levels may be adjusted to change synchronously with the patient's breathing cycle. For example, pressure may be set at one level during inspiration and another lower level during expiration for patient comfort. Such a pressure treatment system may be referred to as bi-level. Alternatively, the pressure levels may be continuously adjusted to smoothly change with the patient's breathing cycle. A pressure setting during expiration lower than inspiration may generally be referred to as expiratory pressure relief. An automatically adjusting device may increase the treatment pressure in response to indications of partial or complete upper airway obstruction or other sleep disordered breathing events. See U.S. Pat. Nos. 5,245,995; 6,398,739; 6,635,021; 6,770,037; 7,004,908; 7,141,021; 6,363,933 and 5,704,345. Treatment pressure produced by such CPAP devices typically range from 4 cm H2O to 22 cm H2O for treatment of OSA, depending on patient requirements. Treatment pressures for assisted ventilation can range of up to 32 cm H2O.
Other devices are known for providing respiratory tract therapy. For example, Schroeder et al. describes an apparatus for delivering heated and humidified air to the respiratory tract of a human patient in U.S. Pat. No. 7,314,046, which was filed on 8 Dec. 2000 and assigned to Vapotherm Inc. Similarly, Genger et al. discloses an anti-snoring device with a compressor and a nasal air cannula in U.S. Pat. No. 7,080,645, filed 21 Jul. 2003 and assigned to Seleon GmbH.
It may be desirable to develop further methods and devices for treating respiratory conditions.